Meet Tolfdir at Saarthal (follow your map icon, but you'll find it near Winterhold and he will take you inside after you speak to him to tell him you are ready. You won't be able to enter without him (the door will indicate that you need a key). Use the wait function if you've beaten him to the door or browse the levels of wooden walkways for some loot.

Once inside you can sheath your sword or spells as there are no enemies in this first section (until after you find some items for Arniel). Follow Tolfdir to the bottom of the wooden stairs and he'll speak to you again. Choose the top dialog option to move on. Tolfdir will ask you to Find Arniel Gane.

You are to meet Arniel, who can be found relatively easily. He's located past the next open cavern so follow the map or the passageways until you get to another cavern, make your way to the bottom and through some more tunnels. Arniel asks you to find four artifacts. Your map will be updated with the location of all four. Follow the corridor to grab three enchanted rings (on the ground) and an amulet. The fourth artifact is the Saarthal Amulet. Once retrieved, you'll be trapped inside the room. Go back to the bars that now block your exit and speak to Tolfdir who will come to help. Do as instructed and use the amulet to escape the trap by equipping it, then cast a spell (any spell) on the wall where the amulet was.

Doing so breaks down the wall, after which Tolfdir passes through expecting you to be behind him. Once in the room, you will have a vision from Nerien, a member of the Psijic Order. After you inform Tolfdir about the vision, he suggests looking around a bit. You might have draugrs to deal with your immediate future. And after speaking to Tolfdir and telling him about your vision a Draugr and a Restless Draugr will burst from their coffins.

Note: If you haven't figured it out by now, Tolfdir has a knack for repeating himself and stopping if you follow him too closely. Let him go ahead and then follow at a safe distance.

Follow Tolfdir around the corner and down the ramp (no enemies). Use the lever on the right to open the gate. Be ready for a fight. As soon as you enter you'll be confronted with a number of Draugr, but they should be easy enough to dispatch with Tolfdir and perhaps a companion, housecarl or follower at your side. This room may be leveled, but you'll have to deal with at least 4 Draugr before you enter into another dialog with Tolfdir.

Tolfdir will stay behind, but asks you to press on. Pull the two chains on either side of the door on the far side of the room to uncover a door to the next area. No one will attack you in the first room so check the small and large burial urns for loot (leveled gold, gems and potions). In the next larger room you'll see a light in the corner. Beware the corner as there is Fire Rune waiting for a misplaced foot (circular mark on the floor glowing orange).

Moving through the room will trigger the Draugrs that are waiting for you, send a firebolt or similar spell down the hall to wake them if you want them to come to you. One will attack in the first section, turn the corner for two more. A third can join the fight from upstairs and he will be a Restless Draugr wielding a bow and arrow so beware if the fight against the first couple starts to drag on. Each will have some gold, weapon (Ancient Nord Sword, War Axe, etc.) and a chance at a gem.

Go upstairs and turn left towards the coffin (empty) and head towards it. A soul gem, coin purse and burial urn will be on your right. Once the need for loot subsides head past the coffin and through the doorway. Gold and potions straight ahead. Go left after and around the corner.

Careful of the poisonous arrow floor trap as you move down the ramp. Beyond this trap are more powerful draugrs depending on your level. They could be anything from a normal Draugr to Restless one and a Draugr Wight. You can touch the poisonous arrow trap to wake them and then fight them as they come up the ramp or go attack them as they wake.

No more enemies in the next room, but you'll have to arrange six pillars to open the door ahead. The solution is on the wall behind each pillar.

Note: It's easiest to temporarily bump up your brightness in-game as the clues will probably be difficult to see under most standard brightness settings (unless you have it at maximum).

The solution from lever facing away from the door (towards the way you came in):

Left: Hawk, Hawk, Whale

Right: Whale, Snake, Hawk

Be careful as a wrong combination will result in some poisonous darts from the walls. Go through the door and around the corner. Ready your nerves and open the next (non-loading) door.

Once opened, your prize is really just another enemy, but in the form of a powerful Draugr Deathlord. He can dole out a lot of pain in a single swing. It's best to take him out from a distance if possible. Feel free to run laps up and down the stairs to keep him on your tail, turn and fight when you are ready. Use your shouts whenever you can to inflict more damage as well. Another strategy involves running back to the room with the pillars and standing next to the lever. As the Deathlord approaches, close the door and shoot him with arrows. This will have to be repeated a lot of times depending on your level.

After defeating, move on up the stairs and through the door. There are two alchemic traps here on the floor. If you go through those traps, you will be hit by lightning. Disable these traps by using some Destruction spells on it a couple of times.

Time to arrange four pillars again in order to open the door. And of course, pulling the lever with incorrectly arranged pillars will shoot poisonous arrows from the wall.

The solution is on top of each pillar, but the pillars here are a bit difficult to shuffle as activating the first or second pillar to the left will also activate the two pillars on the right. And activating the second pillar on the right will activate the first one on the right.

So, here is the combination for rotation:

Rotate the first pillar on the left once.

Rotate the second pillar on the left once.

Rotate the second pillar on the right twice.

The first one on the right can rotate individually so you can rotate that for the correct pillar.

After you open the door Tolfdir will catch up with you. Go around the corner and loot what you will. Beware of the foot trap ahead.

Note: Try to get around a corner quickly, Tolfdir might not avoid stepping on the trap and will probably set it off.

Move to the next room to face Jyrik Gauldurson. When you first walk in nothing will happen, walk to the overlook and you may have to walk part of the way down the ramp on the right to get the sequence to start. Behind Jyrik is a giant sphere. As you move down, though, Jyrik moves into hostile action. You attacks will not affect him. For the first part of the fight use wards or a shield to weaken the damage you take. Feel free to conjure something for Jyrik to attack. Tolfdir will attack the giant ball, which will weaken Jyrik, allowing you to take him out. You'll know you can hurt him because he'll erupt in flames. Kill him. Retrieve the amulet from Jyril's corpse. This will complete the quest for finding the amulet.

Tolfdir will ask you to return to the college and to inform them about the giant sphere that you discovered. Loot the surrounding burial urns and move on. Head to the next room to learn a new DragonShout before leaving.

Back at the College of Winterhold you'll have to find the Archmage Savos Aren (check your map) most likely in his quarters. Enter the Hall of Elements, go through the door on your right and up the stairs. Tell the Archmage what you found.

You'll receive a Staff of Magelight from Archmage Savos Aren as a gift.